OP0161 TREATMENT PATTERNS OF IDIOPATHIC INFLAMMATORY MYOPATHIES: RESULTS FROM AN INTERNATIONAL COHORT OF OVER 1,400 PATIENTS
Authors: M. Aoude, L. Gupta, I. Hmamouchi, S. Grignaschi, L. Cavagna, M. Kim, N. R, J. B. Lilleker, P. Sen, V. Agarwal, S. Kardes, J. Day, A. Makol, M. Milchert, T. A. Gheita, B. Salim, T. Velikova, A. E. Gracia-Ramos, I. Parodis, A. Selva-O’callaghan, E. Nikiphorou, T. Chatterjee, A. L. Tan, M. A. Saavedra, S. Katsuyuki Shinjo, J. Knitza, M. Kuwana, A. Nune, O. Distler, H. Chinoy, V. Agarwal, R. Aggarwal, N. Ziade
Journal: Annals of the Rheumatic Diseases (2022)

Background Idiopathic inflammatory myopathies (IIM) are a group of heterogeneous autoimmune disorders with limited standardization of treatment protocols. Objectives To evaluate frequency and patterns of various treatments used for IIM based on disease subtype, world region, and organ involvement. Methods Cross-sectional data from the international CoVAD self-report e-survey 1 was extracted on Sep 14 th , 2021. Patient details included demographics, IIM subtypes (dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), antisynthetase syndrome (ASSD), necrotizing myositis (NM) and overlap myositis (OM)), clinical symptoms, disease duration and activity, and current treatments. Treatments were categorized in corticosteroids (CS), antimalarials, immunosuppressants (IS), intravenous immunoglobulins (IVIG), biologics, and others. Typical clinical symptoms (dyspnea, dysphagia) were used as surrogate for organ involvement. Factors associated with IS were analyzed using multivariable logistic regression, adjusting for IIM subtype, demographics, world region, disease activity, and prevalent clinical symptoms (&gt;10%). Results In 1418 patients with IIM, median age was 61 years [IQR 49-70], 62.5% were females, median disease duration was 6 years [IQR 3-11], most common subset was DM (32.4%). The most used treatments were IS (49.4%, including Methotrexate 19.6%, Mycophenolate Mofetil 18.2%, Azathioprine 8.8%, Cyclosporine 2.7%, Tacrolimus 2%, Leflunomide 1.6%, Sulfasalazine 1%, and Cyclophosphamide 0.6%), followed by CS (40.8%), antimalarials (13.8%) and IVIG (9.4%). Biologics were used in 4.3% of patients. Treatment patterns differed significantly by IIM subtypes with a higher frequency of IS (77.7%) and CS (63.4%) use in ASSD; antimalarials (28.6%) and biologics (9.8%) use in OM and IVIG use in NM (24.6%) (Table 1). Also, treatment patterns were different in regions of the world (Figure 1), with a higher frequency of CS use in Europe (60.5%) and IS use in South America (77.2%). Antimalarials were most used in Asia (19.4%), while IVIG use was most common in Oceania (16.9%). Dyspnea was associated with higher use of IS (69.9%) and CS (65.8%) (p&lt;0.001), whereas dysphagia was negatively associated with IS (39.7%) and CS (32.7%) likely due to a higher proportion in IBM patients reporting dysphagia. Table 1. Current Treatments for IIM, Stratified by Disease Subtypes Dermatomyositis Polymyositis Inclusion Body Myositis Anti-synthetase syndrome Necrotizing myositis Overlap syndrome All IIM p-value Number of patients 459 182 348 148 57 224 1418 Immunosuppressants* 269 (58.6) 107 (58.8) 39 (11.2) 115 (77.7) 40 (70.2) 130 (58.0) 700 (49.4) &lt;0.001 Corticosteroids 208 (48.0) 81 (46.8) 32 (9.7) 90 (63.4) 32 (59.3) 103 (50.0) 546 (40.8) &lt;0.001 Antimalarials 99 (21.6) 7 (3.8) 0 (0.0) 25 (16.9) 1 (1.8) 64 (28.6) 196 (13.8) &lt;0.001 Intravenous Immunoglobulins 54 (11.8) 16 (8.8) 19 (5.5) 10 (6.8) 14 (24.6) 20 (8.9) 133 (9.4) &lt;0.001 Biologics** 17 (3.7) 7 (3.8) 0 (0.0) 13 (8.8) 2 (3.5) 22 (9.8) 61 (4.3) &lt;0.001 Others*** 6 (1.3) 0 (0.0) 0 (0.0) 1 (0.7) 0 (0.0) 5 (2,2) 12 (0.8) 0.098 *Methotrexate (278), Mycophenolate Mofetil (258), Azathioprine (125), Cyclosporine (38), Tacrolimus (28), Leflunomide (23), Sulfasalazine (14), Cyclophosphamide (9 ) . **Rituximab (44), Abatacept (5), TNF inhibitors (4), Tocilizumab (3), Belimumab (3), Secukinumab (1 ) . ***JAK(10) and PDE4 inhibitors (2 ) Multivariable logistic regression analysis showed an association of IS with the IIM subtype (least used in IBM (OR 0.07 [95%CI 0.04-0.13] compared to DM), world region (most used in South America (OR 2.35 [1.12-4.91] compared to North America), active and worsening disease activity (OR 3.49 [1.76-6.91] compared to remission), and some clinical features (dyspnea, fatigue, and muscle weakness). Conclusion IIM treatment patterns differ significantly by disease subtypes, world regions and organ involvement, highlighting the need for unified international consensus-driven guidelines. References [1]Parikshit S. et al. Rheumatol Int. 2022 Jan;42(1):23–9. Disclosure of Interests None declared